Various kinds of electronic equipment are carried on a motor vehicle. Therefore, the wiring harness is arranged on the motor vehicle so that electric power from a power source and control signals from a computer can be supplied to the electronic equipment. The wiring harness has electric wires and connectors attached to end portions of the electric wires.
The electric wire has a conductive core wire and an insulative covering portion covering the conductive core wire. The electric wire is a so-called covered or sheathed wire. The connector has a conductive terminal fitting and an insulative connector housing. The terminal fitting is attached to an end portion of the electric wire and is electrically-connected with the core wire of the electric wire. The connector housing is formed in a box-shape and accommodates the terminal fittings.
When the wiring harness is manufactured or assembled, the electric wire is firstly cut in a fixed length, and the terminal fitting is attached to the end portion of the electric wire. The electric wires are connected as the need arises. Subsequently, the terminal fitting is inserted into the connector housing. Like this, the above-described wiring harness is manufactured or assembled.
With regard to the electric wire of the wiring harness, the thickness of the core wire, material (for example, from view point of heat-resistance) of the covering portion, and service conditions should be distinguished. Here, the service conditions mean systems such as an air-bag system, an antilock brake system, and a power transmission system in which the electric wires are used.
The electric wires of the wiring harness are variously colored and marked for distinguishing the above systems. When the prior art wiring harness is manufactured, the above coloring and marking are carried out in a process of manufacturing the electric wire by forming the core wire from conductive metal such as copper.
On the other hand, various demands arise from users for the motor vehicle. That is, the motor vehicle is expected to have various kinds of electronic equipment. Consequently, the wiring harness sometimes consists of not less than 100 of the electric wires. Therefore, a factory to manufacture or assemble the wiring harness has to stock not less than 100 of electric wires, while making the stock control of the electric wires having each article number. And therefore, the cost for stocking the electric wires tends to increase.
Further, for example, the electric wire with a determined article number needs to be set in a device to cut off the electric wire in a fixed length. However, since there exists a lot of article numbers of the electric wires, a mistake in the article number of the electric wire would arise. Therefore, the yield of the wiring harness is reduced, thereby causing reduction of the productive efficiency of the wiring harness.
In order to solve such problems, the applicant of the present invention has suggested a wiring harness manufacturing method described in Japanese Patent Application Laid-open No.61-245412. In this wiring harness manufacturing method, the electric wires are colored and marked just before each of the wire manufacturing step, the cutting step, the cover removing step, the terminal-crimping step, and the case insertion step.
With respect to the above prior art wiring harness manufacturing method of Japanese Patent Application Laid-open No.61-245412, however, the coloring and the marking are carried out just before each of the steps of manufacturing or assembling the wiring harness as above.
Therefore, in the wiring harness manufacturing method of Japanese Patent Application Laid-open No.61-245412, a device for coloring and marking the electric wire has to be provided on each of a wire cutting unit, a covering portion removing unit, a terminal crimping unit, and a terminal inserting unit. The prior art wiring harness manufacturing method also requires installation or mounting work of the above coloring and marking device between each two units, and requires the wiring harness to be set on each coloring and marking device.
Like this, in the wiring harness manufacturing method of Japanese Patent Application Laid-open No.61-245412, the number of the coloring and marking device increases, which therefore increases the space for manufacturing the wiring harness.
And also, the coloring and marking work totally requires long time, which lowers the productive efficiency of the wiring harness. Like this, the wiring harness manufacturing method of Japanese Patent Application Laid-open No.61-245412 requires high manufacturing costs of the wiring harness.
In view of the foregoing, an object of the present invention is to provide a wiring harness manufacturing method and a wiring harness manufacturing apparatus, wherein the above drawbacks of the prior art wiring harness manufacturing method and apparatus have been solved and therefore manufacturing costs of the wiring harness can be reduced.